var path = argument0;
var prec = 16;
var step = 1/path_get_length(path) * prec;
tiles = ds_map_create()
 
for (i=0; i<1-step; i+=step)
{
    px = path_get_x(path, i) & ~$f;
    py = path_get_y(path, i) & ~$f;
    tp = tile_layer_find(depth, px-8, py-8)
    if (not ds_map_exists(tiles,tp)) and (tp!=-1)
        break;
    t = tile_add(bck_road,0,0,16,16,px-8,py-8,depth)
    tile_set_alpha(t,1)
    astar_setcellcost(px,py,-3)
    ds_map_add(tiles,t,1)
}
ds_map_destroy(tiles)
